WOW, it's in high definition (1280x720)! Pretty nice!
Hmmm, and a doggy simply walks around...
Once upon a time (25 years ago) I with a girl did the same thing trying to make a dog stuck. The dog was actually a puppy of black terrier, very friendly, very big, and rather stupid. We liquefied the quicksand and pressed at the dog's back until his legs completely sank. Unfortunately, just we released the dog - he was out. Immediately. It took me a bit longer to get out (I was just above my knees in the sand). Then the girl asked, "And who will help me?" She appeared to be waist-deep. Well, nobody wished to get her out, so she had to do it on her own. (Unfortunately, she succeeded). It was very similar (in depth, position, and time to escape) to the girl that gets out the last on the second video
Ahhh, memories...